Cells + internal environment

Question 1

What are the different components of the body? + their %?

Answer 1

• 60% water- decreases with age
• 18% protein
• 15% fat
• 7% minerals

Question 2

Name + define all of the body fluid compartments

Answer 2

Interstitial fluid = thin layer of fluid outside of cells
Blood plasma = all fluid within blood vessels
Intracellular fluid = fluid inside of cells

Question 3

What 2 body fluid compartments make up the extracellular fluid?

Answer 3

Blood plasma + interstitial fluid

Question 4

What is the proportion of water in each body fluid compartment?

Answer 4

1/3 water in extracellular parts- mostly interstitial fluid
2/3 water in intracellular fluid

Question 5

Define: Osmotic Equilibrium

Answer 5

Water can move across different compartments until it reaches the same concentration across them all

Question 6

In what ways can water be lost or gained?

Answer 6

+ Stomach + intestines via eating and drinking
+ Blood vessels
- Vomiting and diarrhoea
- Bleeding
- Respiration
- Kidneys via urine

Question 7

In what ways can water be lost or gained?

Answer 7

+ Stomach + intestines via eating and drinking
+ Blood vessels
- Vomiting and diarrhoea
- Bleeding
- Respiration
- Kidneys via urine

Question 8

Describe the structure of the cell membrane

Answer 8

Phospholipid bilayer = double layer of phospholipid molecules:
- hydrophobic tails = 2 fatty acid chains
- Hydrophillic heads = love water
transmembrane proteins form holes throughout membrane

Question 9

What model is the cell membrane structure usually reffered to as? + why?

Answer 9

Fluid-Mosaic Model:
- fluid = molecules held together by van der waals forces so they can move
- Mosaic = proteins present

Question 10

What are the functions of the cell membrane?

Answer 10

• Structure for cell- in aqueous solution lipids organise into spheres
• Controls intracellular environment- creates a chemical disequilibrium as it has different permeability to different molecules

Question 11

Define: chemical disequilibrium

Answer 11

= different conc of molecules in and out of cell

Question 12

What molecules lead to a chemical disequilibrium of body fluid compartments?
+ Which ones are higher in conc in the intracellular fluid and extracellular fluid?

Answer 12

Intracellular = + potassium, calcium, protein
Extracellular = + sodium, chlorine

Question 13

What factors affect permeability and why?

Answer 13

• size = smaller molecules = more permeable
• • lipid solubility = more permeable
• • charge = membrane less permeable

Question 14

Define: Diffusion and what is it caused by?

Answer 14

= movement from one area of high concentration where there is more collisions to low concentration where there is less collisions

• caused by random collisions of molecules travelling at high speeds

Question 15

Where can diffusion take place?

Answer 15

open systems
or
Boundary between 2 systems

Question 16

Define: osmosis

Answer 16

= movement of water molecules from a high to low conc in response to a solute concentration gradient to balance water levels

Question 17

Define: osmotic pressure

Answer 17

= pressure needed to prevent movement of water

Question 18

Are the fluid compartments usually in a state of equilibrium or disequilibrium?

Answer 18

Osmotic equilibrium

Question 19

What is the function of proteins in cell membranes?

Answer 19

Act as carriers of channels to facilitate flow of substances that cannot permeate the lipid bilayer e.g. ions, larger molecules

Question 20

Define: facilitated diffusion

Answer 20

movement of molecules from high to low conc down the concentration gradient using protein carriers or protein channels

Question 21

How do protein carriers work?

Answer 21

proteins combine to a specific substrate and carries it across cell membrane, where it releases into cell

Question 22

How do protein channels work?

Answer 22

Protein spans across entire membrane and allows movement of substances e.g. ions when open

Question 23

What are aquaporins?

Answer 23

Water channels that move water molecules in a single file via osmosis

Question 24

Define: active transport

Answer 24

Movement of molecules from low to high concentration against the concentration gradient- so energy is required

Question 25

Where does energy for active transport come from?

Answer 25

ATP which is broken down into ADP via ATPase which releases energy

Question 26

Define: endocytosis

Answer 26

movement of substances into cell

Question 27

Name and define 2 types of endocytosis

Answer 27

Pinocytosis = molecules get trapped within vesicles within membrane and are brought into cell

Phagocytosis = arms of cytoplasm encapsulates molecules and brings inside of cell

Question 28

Define: exocytosis + how does it work?

Answer 28

= movement of substances out of cells
- moves hormones + neurotransmitters out of cells via vesicles that fuse with cell membrane to be released outside of cell